Savory Beef Stew With Roasted Vegetables

• 12 mushrooms
• 6 tomatoes (plum)
• 3 garlic (cloves)
• 3 onions
• 800 gr beef bottom round (boneless)
• 475 gr couscous (cooked)
• 38 ml olive oil
• 30 ml water
• 22 ml balsamic vinegar
• 10 ml blasamic vinegar